Hybrid Work Machine and Method of Controlling Auto-Stop of Engine for the Same

Abstract

A hybrid hydraulic excavator includes an engine, a generator motor, a capacitor, a cooling system being configured to cool the capacitor, and a controller. The cooling system includes a circulation mechanism being configured to circulate a cooling water, and a cooler being configured to cool the cooling water with output from the engine. The controller prohibits auto-stop of the engine when it is determined that the capacitor is overheated.

Description

TECHNICAL FIELD[0001]The present invention relates to a hybrid work machine equipped with a capacitor and a method of controlling auto-stop of an engine for the hybrid work machine.BACKGROUND ART[0002]As a work machine, there has been known a hybrid work machine such as an excavator in which an engine drives a generator motor and a hydraulic pump, whereby an electric motor for an upper rotary body, in which a cab and the like are provided, is driven by electric power generated by the generator motor while a hydraulic actuator for a working equipment and a hydraulic motor for a traveling device are driven by a pressure oil from the hydraulic pump. The electric power generated by the generator motor is charged in a capacitor serving as an electric storage device and is outputted from the capacitor to the electric motor through an inverter. In other words, while a hybrid automobile uses a secondary battery with a high energy density as an electric storage device, a hybrid work machine ...

AI Technical Summary

Benefits of technology

The patent text explains that when an engine is stopped to save fuel, the cooling function of the vehicle's devices becomes less effective, which can cause them to overheat. This is particularly problematic for a capacitor used in a hybrid work machine, as it can decrease its capacity and cause premature wear and tear. The technical effect of the patent is to provide a solution to prevent the overheating of devices in a vehicle during idle stop operations.

Problems solved by technology

Since an engine is stopped when auto idle stop is in operation, a cooling function becomes less effective and thus the operation temperatures of devices equipped in a vehicle are likely to rise beyond an appropriate operation-temperature range.

In particular, when a capacitor used in a hybrid work machine is heated to a high temperature, the capacitance thereof is decreased and thus the charging / discharging performance is deteriorated.

Further, the high temperature operation of the capacitor increases a decrement of the capacitance, which results in shortening the lifetime of the capacitor.

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